Liquid material supply system



L37 ll Dec. .16, 1941. A. CHRISTENSQN TAL l 2,266,354

l a l l. IIQUIDMATERIAL SUPPLY SYSTEM Filed March 22, 19:59

Z0 20 v 20p 57 L? 16X L? i Patented Dec. 16,1941.

LIQUID MATERIAL SUPPLY SYSTEM Alfred W. Christenson, Detroit, and Frederic G. Garrison, Birmingham, Mich., and Eric Gustafsson, Chicago, Ill., assignors to Binks Manufacturing Company, Chicago, Ill., a corporation of Delaware Application March z2, 193s, serial No. 263,338

3 Claims.

The present .invention relates to systems for distributing fluidal materialI including various coating materials, such as paints, enamels, lacquers, or the like, and has reference more particularly to a system of the circulating type.

Coating materials are supplied under pressure through pipe lines extending along stations where the material is applied to the objects to be coated at the stations, as by means of spray guns, there being a pipe line for each character of material, and a spray gun at each station for each pipe line'. The spray guns are connected to the pipe lines at the stations by supply ducts, such as hoses. As the guns are opened and closed, the demand for the material is accordingly varied and there is generally, in the usual circuit, also a variation of pressure of the material in the line.

The present invention comprehends the provision of a novel means for,las well as a novel method of, supplyingor feeding the material to the line in accordance with the demand made by the guns and also constantly maintaining the predetermined pressure of the material in the line so that the spraying by any gun will be unaffected by the opening and closing of other guns connected in the same line, the spraying being always proper and as desired.

These objects are accomplished by including in the circuit, as at the end of the main or supply portion of the circuit and just after the last gun on the line, or at the end of the return circuit portion, an adjustable, automatic regulating or modulating valve, so that such valve may act upon any tendency to change of pressure'in the line to counteract it and immediately effect the necessary flow of material to the line in accordance with the demand made bythe guns. The circuit includes a feed-back circuit in which such a valve is connected.- Thisvalve so controls the owr'in the feed-back as to either throttle such ow or to permit greater flow of material in accordance with the tendency to decrease or increase of pressure, respectively, of the material in the feed or supply line. When such a valve is used in the return line, it acts likewise to eect its counteracting action by way of the return portion of the line or circuit.

Fig. 1 is a-diagrammatic showing of Aa circulating, distributing system constructed in accordance with the invention;

Fig. 2 is a similar fragmentary showing of an alternative form: and

Fig. 3 is a similar fragmentary showing of an alternative feed back arrangement,

Referring more in detail to the drawing, the embodiments chosen to illustrate the invention in more or less diagrammatic form on 'the drawing are shown as comprising a feed or supply pipe line or circuit portion I and a return pipel line or circuit portion 2. 'Ihe line I is connected by way of a suitable lter 3 and a pump discharge main 4 to a suitably operated pump 5, an intake 6 to the pump being connected to the lower end of a material container 1. A by-pass pipe 8 may be connected to the pump discharge pipe 4 and the feed line I to by-pass the material whenever it is necessary to clean the filter.

From the pump discharge 4 runs a feed-back pipe il by way of a modulating or regulating valve III to and into the upper part of the containerpr tank l, for the feed-back of the material in excess of that neededV in the main line I, the valve I0 being so adjusted as to maintain a given pressure in the main line I. This v'alve is of the known adjustable automatic type wherein when the pressure rises on the inlet side of the valve the latter automatically opens to permit the passage of more material therethrough and to thus s cause -a reduction of the excessive pressure, and

when the pressure on the inlet side of the valve drops below the point for which the valve was adjusted it will then throttle the flow of material through it to effect an increasein pressure toward and to the predetennined point for which the valve was set.

There is also connected in shunt with the feedback 9 a relief circuit vII with a suitable relief valve I2 between the pump discharge 4 and thev `material in homogeneous condition. The return line 2 is connected by way of a valved pipe I4 to the upper part of the tank 1, and may have a modulating or regulating valve III* of the same kind as valve III in the feed-back 9. This valve II)n is so connected in the return line as to open when there ls an increase of pressure in the return line on the inlet side of the valve above a predetermined point for which the valve was set, to allow more material to pass to the tank and thus decrease the excess pressure, and to throttle the flow of material when the pressure in the return line on the inlet side of the valve decreases below the point for which the valve. was set, so

as to build up or bringback the pressure to `the e predetermined point. The valvell functions i to automatically maintain a given back pressure in the return line 2.

In the form shown in Fig. 2, in lieu of having the modulating or regulating valve III* at the end y of the return portion lof the circuit, such valve Il may be located at the end of the supply prtion of the Circuit, preferably just after the last gun on the line I. Thus valve IIIb functions to automatically maintain a given pressure in the line I. Y

In either case, or in both cases (Figs. 1 and -2) the pressure in line I is maintained by reason of having the regulating valves at both ends, so to speak, of the supply line, that is, valves III and IUI, or valves I Il and Inh, whereby the pressure of the material in the line or circuit between such is connected by a duct 9' which leads back to the 25v are given only as examples. The adjusting and tank 1 at the point where pipe 9 in Fig. 1 is connected. In this way, the modulating valves Il each spraying stationj' and each gun is connected by a'material supply duct I6, such as a hose, to

the feed line I ata point corresponding to the spraying station of'the gun. 'Ihe gun is also connected by an `air supply duct I1, such as a hose, to a pressure air supply main I8, also at a point corresponding with the spraying station. The duct I6 is connected to the feed line I by way of a pressure regulating or reducingv valve I! 45 and a valved pipe connection 20. The valve I9 is of the known adjustable automaticpressure Are ducing type of valve, which when set for a given pressure on the outlet side of the valve functions to open or close with decrease or increase of pressure from the predetermined point on such outlet side ofthe valve, to bring the pressure back tothe given point. A suitable gauge 2I is connected to each valve I! to indicate the pressure on the outlet side of the valve.. Suitable gauges 23 Aand 22 are respectively connected'to the feed line I'and'return line 2te 'indicate the pressures therein. Suitable gauges 24, 25, 26 and 21 are connected to the inlet side of the modulating Y. valves VIII, I0, I0", and I 0 to indicatethe prestures on such side of the valves. Suitable valves,

auch ashand operated valves, are` connected at various points of the system and are shown according to w ell known convention.

By the present invention the material is supplied or fed in accordance with the demand made at the guns, andthe desired pressure in the feed line I is maintained constant, while at the same time there is a circulation of the material in the -70 proper pressure is maintained-in the feed line.

circuit I.-2, and in the feed-back 9. The amolmt "so circulating `or feeding back will be generally i0 the inlet sides of the valves I9.

material isfe'dtotheline Landpartisfedback to the tank 1 by way of the feed-back circuit 9. The modulating valve is so adjusted and set as to maintain a given pressure in the feed line, such as, for example, 50 poundsat the last take-ofi or gun at the end of the line I. The valves I9 are so adjusted and set as to maintain a given pressure at the guns whether spraying or not spraying and regardless of the pressure in the line I and at 'I'he pressure for which the valves I9 are set may be, by way of example, 30 pounds. The modulating valve III* in the return line is so adjusted and set as \to effect that back pressure in the return line as i5 to assist in maintaining the predetermined pressure in the feed line I. By way of example, the valve Illn may be set for l0 pounds pressure at the inlet side of `the valve. When valve II)b is used (see Fig. 2) at the end of the supply line I,

it is so adjusted and set as to effect that pressure in the line I as to maintain it at the desired value, such as 50 pounds, at the last gunof the series. Under 'such conditions, the pressure in .the valve I0h may be 55 pounds. These values setting depend upon the desired pressure to be maintained in the line I.

In operation 'when any gun is opened to spray there is a tendency to a drop of pressure in the hose I6. Immediately the valve I9 acts to a counteract such tendency andtopermit the passing through' of the required material to the gun. This is immediately eifective through 'the line to the modulating valves Il and I0s or Nb. The

'35 -valve 'Il immediately acts to throttle the flow of material in the feed-back 8 so that such material, which 'would otherwise be fed back to the tank 1, is fed to the line I to meet the demand made by opening the gun and also to maintain the given 40 pressure in the line l. 'I'he tendency to drop in pressure in the line I is effective directly in the valve Il or indirectly through the return 2 in the valve Il, In either case, the valve Ilb or III to or vthrough 'the return .line 2, and maintains the given'or desired pressure in line I. 'I'he same results occur when more guns are opened regardless of the number.

When any gun is closed,'there is a tendency toward an increaseof pressure in the hose I6, in line I and iri'line 2. Immediatelythe valves Il and Il* or Il act to open so as to let more material flow to the tank 'L by way of the feed 1.55 back S and the return line 2 connectedto the tank, thus counteracting such tendency at both ends of line I, so to speak. The valve I9 also acts to reduce or stop the flow to hose Ii but to maintain in hose Il the desired pressure on the material so that when the' gun is opened the ma.-

terial will be at the proper pressure for spraying. 'I'he system`is very sensitivev and operates instantaneously so that there is a constant maintaining of the desired and predetermined pres- 35 sures, especially'in the line I. Also, the feed of.

' There is a trend in-paint circulating and dis` 'tributing to use higher viscosity coating materials than heretofore, longer pipe lines, and more' heavily loaded lines. It becomes important in the pump discharge. The main portion of the '(5 in view of such conditions to reduce pump presimmediately acts to throttle the ilow of material sures for the purposes of saving power, luni of reducing pump maintenance cost.

The practice of throttling at the return end of a circulating line by a'v hand operated gate valve, or the like, for building up sufficient pressure at the locus where the regulating valve for the last gun of theseries is connected to the line, is satisfactory only so long as the coating material drawn off by the guns is slight in comparison with the total volume being circulated in the main line. "Under such conditions, the variation in the volume of the liquid passing through the throttling valve, at any given opening, is not great, so that the variation in pressure of the fluid at the locus referred to is correspondingly lslight. Likewise, there is but a; small variation tion in pressure in .the line is small enough to be negligible.

In large installations having long lines, such as v2,000 to 3,000 feet long,.and having al large number of guns connected theretoysuch guns,`

when'all open, will impose a large demand on the supply of material in the line, such as fty per cent (50%) or more of the paint or other coating material supplied by the pump. This means in the usual system a very great variation in pressure of the material in the main line between the ,no-load condition, when all the guns are closed, andthe full-load condition, when all the guns are open.

The present invention eliminates or prevents such variables, by so placing automatically oper- Having ,thus disclosed the invention we claim:

1. A fluid material supply system comprising a circuit including a source of supply and means connected thereto for forcing material continuously through the circuit, saidcircuit including a supply circuit portion and a return circuit portion, material applying appliances connected to said supply circuit portion, pressure reducingvalves connected thereto and responsive to the pressure of the material at the appliances to control the supply of material from said supply circuit portion to the appliances, a feed-back means connected to van end of said supply circuit por- 'tion and to said source of supply for continuoustion, material applying appliances connected to said .supply circuit portion, pressure reducing ating regulating or modulating valves at such points in thecircuit as to be immediately eiIective at both ends of the supply line formaintaining a constant or uniform pressure of material in the line regardless of the variation in load, the volume of material supplied by the pump to the feed line being proportionate to the demand made by the guns.

Preferably the regulating Valve in the circulating main line is placed just after the last gun of the series so that it will act directly upon that portion of the circuit where thegims are connected, but such valve may be connected to the circuit at the end of the return line. In the latter case, the control is more indirect, by way of the return line, and must be so adjusted as to compensate for such variations as might arise fromthe friction of the liquid in the return circuit portion, and possibly other factors.

By experiments and trials, a-system in accordmaintaining a pressure of 5 5 pounds at the valve lub, and a pressure atv the gunsl of 30 pounds,

f under all load conditions. In other systems not using the present invention, the pump pressure valves connected thereto and responsive to the pressure of the material at the appliances to control the supply of material from said supply circuit portion to the lappliances, a feed-back means I connected to an end of said supply circuit portion and to said source of supply for continuously feeding back surplus material, said feedback means including a modulating valve responsive to the pressure of material in said supply circuit portion for varying the feeding backof the surplus material in inverse proportion to the demand made by the appliances on the material from said supply circuit portion, and a modulating valve connected to the other end of said of surplus material by way of said return circuit vportion to said'source of supply in inverse proportion to the demand made by the appliances on the material from said supply circuit portion.

3. A fluid material supply system comprising a circuit including a source of supply and means connected thereto for forcing material continuously through the circuit, said circuit including a supply circuit portion and a return circuit portion, material applying appliances connected to said supply circuitqportion, pressure reducing valves connected thereto and responsive to the pressure -of the material at the appliances to control the supply of material from said supply circuit 'portion to the appliances, a feed-back means varied between 101 and 165 pounds while the v which .includes said return circuit portion for continuously feeding back surplus material from an end. of said supply circuit portion to said source and including a modulating valve responsive to the pressure of the material in said supply circuit portion for varying said continuous feeding back of the material by way of said return circuit portion to said source of supply Iin inverse proportion to the demand made by the appliances on the material from said supply circuit portion.

. ALFRED W. CHRISTENSON.

FREDERIC G. GARRISON. ERIC GUSTAFSSON. 

